The monolithic fabrication of microfluidic systems using additive manufacturing technology offers a promising route for integrating the multifunctionality essential to these devices. However, this approach faces key challenges, primarily due to the limited availability of suitable materials and the incompatibility of these materials during the various processing stages. This study introduces a highly stable, low-temperature phosphate glass for fabricating multifunctional microfluidics via multimaterial additive manufacturing. The synthesized glass powder is formulated into a printable ink using a temperature-sensitive binder, enabling extrusion-based printing at room temperature. The selected glass composition, containing 10 wt% F2O3 as an additive and Na2O as a modifier, exhibits high stability (LogDR = -8.47342 g cm-2 min-1 at 25 degrees C) and a low glass transition temperature (412 degrees C), enabling the functional integration of multiple materials via multimaterial 3D printing. To demonstrate functionality, a microfluidic device incorporating conductors and a mixer is fabricated, where silver paste is used for conductors, polymer paste is used as a sacrificial material, and glass ink as the structural component. All materials are printed simultaneously, demonstrating monolithic additive manufacturing of microfluidic systems. This approach enables the integration of glass, metal, sacrificial materials, and potentially silicon and electronics, paving the way for advanced multifunctional microfluidic devices.

Additive fabrication technologies are very attractive for use in the realization of customized medical diagnostic and point-of-care devices in the rapidly growing field of personalized healthcare. However, non-idealities in additive manufacturing processes, such as the enhanced roughness that is inherent to many such processes, limit the use of these fabrication technologies in real products. In this work, the effect of additive fabrication-induced surface roughness on fluid flow within material extrusion (MEX) 3D-printed microfluidic devices is modeled and experimentally validated. An optimization process to eliminate such effects in functional 3D-printed devices is developed. By the resulting careful model-driven optimization, high-performance printed glass and Acrylonitrile butadiene styrene (ABS) valveless micropumps are demonstrated in this work for the first time. Water flow rates of 210 mu l min(-1) and 140 mu l min(-1) for the ABS and the glass micropumps respectively, and a maximum working backpressure of 978 Pa at an actuation signal of 68 Hz and 120 V pp are achieved, attesting to the viability of additive fabrication to realize functional microfluidic devices.

In this work, we provide a mechanistic understanding of the degradation of perovskite solar cells in operation by focusing on methylammonium lead triiodide (CH3NH3PbI3 or MAPbI3) and tracking the evolution of electronic defects via photo-induced current transient spectroscopy (PICTS). Moreover, we also record the degradation of its photovaltaic characteristics over time under various electric load and temperature conditions. Using PICTS, we found that bands of trap states, initially highly localized deep within the band gap of the perovskite, widened over the exposure period. This effect was exacerbated with increasing temperature. Further, using the design of experiment methodology for this multifactorial study, we found that two interaction factors (temperature load & temperature time) were significant in the degradation of the perovskite cells, validating the importance of our holistic approach. Through these observations, we establish a mechanistic link between deep-level trapsand photovoltaic characteristics.

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The combination of imprinting and extrusion overprinting of composite glass materials offers a pathway for the fabrication of fully integrated functional microfluidic devices. Utilizing novel low-temperature phosphate glasses, originally developed for 3D extrusion printing, imprinting now has been achieved with soft stamps. The current hybrid process demonstrates superior resolution compared to previously reported extrusion techniques, presenting possibilities for applications such as open microfluidic channels that can subsequently be sealed by extrusion printing. The water-based microparticle glass-ink enables patterning at room temperature and its solidification occurring through water evaporation within the glass particle scaffold. Following the demolding, sintering is conducted at a temperature of 485 °C, resulting in dense glass elements with porosity levels below 1 %. For straightforward microfluidic channel structures featuring channels ranging from 100-200 µm in width, the shape is fully preserved during demolding and sequential annealing. The shrinkage observed is almost isotropic. The channels were successfully tested in an open microfluidic setup and initial tests were performed with the closed channels.

Microsupercapacitors (MSCs) are attractive energy devices for applications in IoT, wireless sensors, and other microelectronic systems due to their small footprints.

Microsupercapacitors (MSCs) are attractive for use as energy devices to power wearables, IoT, and other small microsystems. Additive fabrication of these devices will facilitate easy integration into a range of ubiquitous microsystem platforms. In this work, MSCs with lateral sizes < 0.5 cm(2) (full package: 7 mm x 7 mm and charge storage active area: 4 mm x 3.5 mm) and total height of similar to 2 mm with remarkable electrochemical performance are fully 3D printed via a combination of FDM printing and 3D extrusion-based printing. By fine-tuning the chemistries of the components of the MSCs, a combination of high energy density of 16.1 mu Wh.cm(-2), power density of similar to 3028 mW.cm(-2), areal capacitance of similar to 323 mF.cm(-2), and similar to 91.3% capacitance retention after 21000 cycles are realized. These performance levels are achieved using novel inks for the electrodes, electrolytes, and current collectors in addition to provision of proper packaging and encapsulation of the devices. The demonstrated performance of these encapsulated millimeter-scale fully additively fabricated MSCs with thick electrodes (i.e., similar to 300 mu m) thus makes them attractive for use as integrated energy sources for powering microsystems, wearables, and IoT.

A novel 3D fabrication technique called digital LIGA is proposed, integrating functional digital printing with 3D microfabrication via electrodeposition. This allows for the realization of complex multilevel metallic structures without problems associated with merging growth fronts. To achieve this, we developed a gold nanoparticle ink, compatible with a SU-8 photoresist, for printing the digitally-defined seed layers. Using this ink, selective printing of a conductive seed layer on a multi-level photoresist was used along with subsequent electrodeposition. Defect-free complex multilevel metallic 3D structures were successfully prepared via this method.

This work describes the formulation of a stable platinum nanoparticle-based ink for drop-on-demand inkjet printing and fabrication of metallic platinum thin films. A highly conductive functional nanoink was formulated based on dodecanethiol platinum nanoparticles (3-5 nm) dispersed in a toluene-terpineol mixture with a loading of 15 wt %, compatible with inkjet printing. The reduced sintering temperatures (200 °C) make them interesting for integration in devices using flexible substrates and substrates that cannot tolerate high-temperature exposures. A resistive platinum heater was successfully printed as a demonstrator for integration of the platinum ink. The platinum nanoink developed herein will be, therefore, attractive for a range of applications in biology, chemistry, and printed electronics.

Copper-silver (Cu-Ag) core-shell nanoparticles are promising for replacing the silver particles and flakes used in printed conductors in current solar cells since they deliver good conductivity, chemical stability, and optical performance, while also reducing the silver content, thus significantly impacting the cost. The bare nanoparticles offer excellent air stability thanks to the silver-covered copper structure. We demonstrate a screen-printable paste for use in solar cell conductor applications. We report a printed morphology and light reflection properties similar to those achieved with commercial silver pastes. The reported Cu-Ag core-shell paste is uniquely formulated with an epoxy binder and an aliphatic hardener, delivering significantly improved electrical conductivity, while simultaneously reducing the overall silver content by similar to 36 wt %. This is attributable to the cross-linked polymeric structure, low-temperature conversion, and improved loading of conductive core-shell nanoparticles. As needed for contact formation in conventional top-contact silicon solar cells, the paste is additionally loaded with lead bisilicate and delivers conductivity on par with that of commercial silver paste. Thus, by combining the reduction of the silver content with excellent electronic and optical properties, this Cu-Ag nanoparticle-based paste becomes attractive for low-cost printed-conductor applications, including photovoltaics and electronics.

High-throughput printing-based fabrication has emerged as a key enabler of flexible electronics given its unique capability for low-cost integration of circuits based on printed thin film transistors (TFTs). Research in printing inorganic metal oxides has revealed the potential for fabricating oxide TFTs with an unmatched combination of high electron mobility and optical transparency. Here, we highlight recent developments in ink chemistry, printing physics, and material design for high-mobility metal oxide transistors. We consider ongoing challenges for this field that include lowering process temperatures, achieving high speed and high resolution printing, and balancing device performance with the need for high mechanical flexibility. Finally, we provide a roadmap for overcoming these challenges with emerging synthetic strategies for fabricating 2D oxides and complementary TFT circuits for flexible electronics.

This roadmap includes the perspectives and visions of leading researchers in the key areas of flexible and printable electronics. The covered topics are broadly organized by the device technologies (sections 1–9), fabrication techniques (sections 10–12), and design and modeling approaches (sections 13 and 14) essential to the future development of new applications leveraging flexible electronics (FE). The interdisciplinary nature of this field involves everything from fundamental scientific discoveries to engineering challenges; from design and synthesis of new materials via novel device design to modelling and digital manufacturing of integrated systems. As such, this roadmap aims to serve as a resource on the current status and future challenges in the areas covered by the roadmap and to highlight the breadth and wide-ranging opportunities made available by FE technologies.

Vacuum-sealed fully integrated diode and triode field emission arrays based on Ti Spindt-type field emitters have been developed in a scalable, CMOS-compatible process directly on Si. Diode characterization in air demonstrates effective vacuum sealing and field emission conduction, with current drivability that scales with array size. Triode characterization in vacuum demonstrates gate-modulated field emission of the output current and highlights new effects observed in a fully integrated geometry with closely spaced electrodes. Demonstrating up to 200-V blocking voltage and similar magnitude punchthrough voltages, the arrays can be utilized as high-voltage devices in CMOS applications or with microelectromechanical systems (MEMS) technologies using post-CMOS MEMS integration techniques. Low-temperature measurements reveal areas of improvement for electrode isolation; combined with the use of improved cathode materials, these devices have the potential to be used in high-power applications.

Semi solid flow batteries (SSFB) are developed by forming suspensions of electrochemically active and conductive particles for use as an anolyte or catholyte in a redox flow battery. By utilizing micron-scale powders from mature battery chemistries in a flowable suspension, the benefits of energy-dense intercalation chemistries with the scalability of flow battery architectures can be combined for low cost electrochemical storage. Presently, a narrow set of materials has been explored, focusing on chemistries with a lithium anode. In this work, a magnesium SSFB with an optimized MoS2 cathodic slurry is demonstrated as a low cost, high material abundance alternative to lithium-based chemistries. A mixed ionic-electronic conductive network is designed around a dual-ion (Mg, Li) electrolyte, by combining the all-phenyl complex (APC) + LiCl, MoS2, and ketjen black (KB) to form the cathodic slurry. The rheological, electrical, and electrochemical properties of MoS2-KB-APC slurries with varying compositions have been measured. Full cells, with a Mg foil anode and MoS2 slurry cathode, are shown to cycle reversibly for 20 cycles at C/5 in a non-flowing configuration, reaching 180 mAh/g discharge capacity. LiCl concentration and KB concentration are identified as critical to high capacity slurry cathodes. The relative impacts of Mg and Li ions are quantitatively analyzed, showing that both ions are reversibly intercalated during cycling. Finally, a custom flow cell is used to demonstrate 120 mAh/g discharge capacity at C/8, highlighting the flowable nature of the cathode suspension. This work provides experimental data and insight into how existing low cost material sets can be utilized in a semi solid flow battery architecture. Figure 1

Printed electronics has promised to deliver low-cost, large-area and flexible electronics for mass-market applications for some time; however, so far one limiting factor has been device performance. Over the last decade, great progress has been made in terms of materials, processing and printing resolution for printed transistors. In this article, we review dimensional scaling of printed organic thin-film transistors, which has enabled high-frequency operation. We review different device architectures that require different dimensions to be scaled with accompanying tradeoffs in performance and complexity. Various printing methods have been used to print scaled transistors. Inkjet and gravure printing have seen the greatest improvements. We will focus on gravure printing here as it not only enables high-resolution features but also high-speed printing for low-cost manufacturing. Operating voltage has been scaled down less aggressively due to difficulties with scaling down the thickness of printed gate dielectrics. The performance of organic semiconductor materials has also improved substantially. When processing the semiconductor, the scaling of other device dimensions needs to be considered to optimize performance. Based on these advances, transistor switching frequency has increased dramatically over the last decade with several reports of high-speed printed inverters operating at high kHz to low MHz frequencies, which are promising results for emerging applications of printed electronics.

Metal oxides have broad multifunctionality and important applications to energy, sensing, and information display. Printed electronics have recently adopted metal oxides to push the limits of performance and stability for flexible thin film systems. However, a grand challenge in this field is to achieve these properties while balancing the thermal budget, which critically determines the applicability, flexibility, and cost of these systems. This paper presents a focused review of printed metal oxide electronics, highlighting our recent work developing high-performance, printed transistors processed at low temperatures via aqueous precursor chemistries, nanomaterial hybrid inks, and ultraviolet annealing. These results reveal the potential for printing uniquely high-performance active devices (electronic mobility >10 cm(2) V-1 s(-1)) but also illustrates the utility of nanocomposites that integrate nanomaterials within a metal oxide matrix for improving device performance.

Developing low cost energy storage for integrated electronics depends on the ability to increase energy densities while reducing materials and manufacturing costs. Among the several next generation battery chemistries currently being explored, Zn-air batteries are well suited to tackle these challenges and power a wide variety of electronics applications. Zn-air batteries provide a high theoretical energy density, exhibit high performance at high discharge rates, and use low cost, earth abundant materials. Additionally, Zn-air batteries utilize aqueous, non-flammable electrolytes and can be processed entirely in air, making them an emerging candidate to replace Li-ion batteries. Despite their significant promise, side reactions at the Zn anode limit Zn-air battery performance and reduce practical energy densities. Zn corrosion follows a complex series of intermediate reactions in an alkaline environment and is highly dependent on properties of the electrolyte (OH- concentration and use of additives), properties of the electrode (film porosity and active particle size), and cell operating conditions (temperature, current density, depth of discharge, and cell geometry). Thus, each of these factors can alter the fundamental Zn corrosion mechanism and need to be studied systematically to understand their influence on Zn-air battery stability and performance. Previous studies on Zn corrosion have identified single factors that influence reactions at the anode, but typically rely on ex-situ characterization methods that are not representative of the transient and non-equilibrium nature of electrochemical interfaces. In this work, we investigate corrosion in printed Zn-air batteries through the use of operando characterization techniques including differential electrochemical mass spectroscopy (DEMS), X-ray diffraction (XRD), and X-ray absorption spectroscopy (XAS). This approach couples electrochemical measurements with chemical and structural information to directly probe the reaction products at an electrochemical interface and observe non-equilibrium reactions in real time. Moreover, Zn-air batteries are rapidly processed using additive manufacturing in order to investigate several experimental factors in parallel and determine their impact on Zn corrosion. Using this combined approach, we aim to understand which experimental factors significantly influence Zn corrosion in order to identify methods for mitigating self-discharge and improving Zn utilization in Zn-air batteries. DEMS experiments, coupled with operando pressure decay analysis, are used to quantify hydrogen evolution rates at the Zn anode and are used to compare corrosion rates across various cell designs. Through this technique, we examine the effects of current collector type, electrode mass loading, electrode size, and electrolyte concentration on Zn corrosion rates. Based on our results, electrolyte concentration and current collector material have the greatest influence on corrosion rate among the factors studied, while electrode size and electrode mass loading have little effect on corrosion rates. Through operando XRD, we confirm the formation of a passivating oxide layer at the Zn anode and observe that higher electrolyte concentrations lead to faster passivation of the anode under both discharge and open-circuit conditions. Cell potential is also measured during these experiments and is correlated to the fractional amounts of Zn and oxide species in the anode, suggesting that cell potential can be used as a marker for battery lifetime. In addition, operando XAS experiments show characteristic shifts in the Zn K-edge during the passivation process, corresponding to a change in the Zn valence state during oxidation. These shifts are highly dependent on electrolyte concentration, but show little dependence on electrode geometry or mass loading.

Printed batteries are an emerging solution for integrated energy storage using low‐cost, high accuracy fabrication techniques. While several printed batteries have been previously shown, few have designed a battery that can be incorporated into an integrated device. Specifically, a fully printed battery with a small active electrode area (<1 cm2) achieving high areal capacities (>10 mAh cm−2) at high current densities (1–10 mA cm−2) has not been demonstrated, which represents the minimum form‐factor and performance requirements for many low‐power device applications. This work addresses these challenges by investigating the scaling limits of a fully printed Zn–Ag2O battery and determining the electrochemical limitations for a mm2‐scale battery. Processed entirely in air, Zn–Ag2O batteries are well suited for integration in typical semiconductor packaging flows compared to lithium‐based chemistries. Printed cells with electrodes as small as 1 mm2 maintain steady operating voltages above (>1.4 V) at high current densities (1–12 mA cm−2) and achieve the highest reported areal capacity for a fully printed battery at 11 mAh cm−2. The findings represent the first demonstration of a small, packaged, fully printed Zn–Ag2O battery with high areal capacities at high current densities, a crucial step toward realizing chip‐scale energy storage for integrated electronic systems.

Inorganic transparent metal oxides represent one of the highest performing material systems for thin-film flexible electronics. Integrating these materials with low-temperature processing and printing technologies could fuel the next generation of ubiquitous transparent devices. In this work, we investigate the integration of UV-annealing with inkjet printing, demonstrating how UV-annealing of high- k AlO x dielectrics facilitates the fabrication of high-performance InO x transistors at low processing temperatures and improves bias-stress stability of devices with all-printed dielectrics, semiconductors, and source/drain electrodes. First, the influence of UV-annealing on printed metal-insulator-metal capacitors is explored, illustrating the effects of UV-annealing on the electrical, chemical, and morphological properties of the printed gate dielectrics. Utilizing these dielectrics, printed InO x transistors were fabricated which achieved exceptional performance at low process temperatures (<250 °C), with linear mobility μlin ≈ 12 ± 1.6 cm2/V s, subthreshold slope <150 mV/dec, Ion/ Ioff > 107, and minimal hysteresis (<50 mV). Importantly, detailed characterization of these UV-annealed printed devices reveals enhanced operational stability, with reduced threshold voltage ( Vt) shifts and more stable on-current. This work highlights a unique, synergistic interaction between low-temperature-processed high- k dielectrics and printed metal oxide semiconductors.